Stdout as IO object

[Jonathan Bale]

Okay, real simple question, but somehow I am missing it in the API: how
do create an IO object that represents stdout? I'm using a certain
function that receives writable IO objects and I wanted to pass in the
standard output as a stream.

 

[Ammar Ali]

[Note: parts of this message were removed to make it a legal post.]

Okay, real simple question, but somehow I am missing it in the API: how
do create an IO object that represents stdout? I'm using a certain
function that receives writable IO objects and I wanted to pass in the
standard output as a stream.

Why not just pass $stdout itself?

Ammar

 

[Brian Candler]

Okay, real simple question, but somehow I am missing it in the API: how
do create an IO object that represents stdout? I'm using a certain
function that receives writable IO objects and I wanted to pass in the
standard output as a stream.

When your program starts, the constant STDOUT is an open file descriptor
for STDOUT, and the global variable $stdout also points to it.

Using the global variable is the recommended approach, as it adds more
flexibility for pointing it to a different object like a StringIO
without having warnings about constants being redefined.

 

[skim]

[Note: parts of this message were removed to make it a legal post.]

Instead of modifying the global variable $stdout, you could just pass in an
instance of StringIO to your method/class. I passed in two instances of
StringIO to one of my classes for mocking STDIN and STDOUT.

 

[Jonathan Bale]

When your program starts, the constant STDOUT is an open file descriptor
for STDOUT, and the global variable $stdout also points to it.

Using the global variable is the recommended approach, as it adds more
flexibility for pointing it to a different object like a StringIO
without having warnings about constants being redefined.

The $stdout variable works fine. I was a little confused with $stdout at
first, because the documentation I found either does not describe what
it is, or talks about it as a "file descriptor". But it is actually an
IO object:

$ irb
irb(main):001:0> $stdout.class
=> IO